Went to lunch and they were just fine, of course. They were told if there was fighting, pantry raiding or irresponsible behavior of any kind, I wouldn't be able to trust them and it would be back to the babysitter.
First movie ended before I got back so they fired up another one. They barely noticed I was gone.
Thanks for all the responses! I think we are going to hold off on being alone at night for a while longer.